1. Field of the Invention
The present invention is related to an injection molding device, system, and method. Specifically, an injection molding device, system, and method using asymmetrical nozzles, flat nozzles, or flat micro nozzles. The present invention is further related to arrays of asymmetrical nozzles, flat nozzles, or arrays of flat micro nozzles that are tightly spaced along a preferred direction.
2. Background
In the production of small injection molded objects and of objects having a small dimension along a certain direction, it is ideal to use an array of tight or small pitch injection systems in order to increase the output per injection cycle without increasing the overall foot print of the entire system. (e.g., systems that have a small or tight spacing between adjacent nozzles or adjacent injection molding parts). One problem that arises is that, while the injection molding devices (e.g., nozzles) have become increasingly smaller (e.g., micro nozzles), it has become more difficult to provide a uniform temperature profile in various areas of the nozzles. Typically, injection nozzles have a heater element, such as a tubular, thin film, band heater, embedded heater or helical coil heater that are wrapped around the nozzle body. There are also injection nozzles including cartridge heaters and heat pipe heaters located inside the nozzle body along the melt channel. Spacing available within the nozzle for the heater element decreases as pitch specifications require smaller or thinner pitches.
Every molding process has a required tolerance for a temperature window and a temperature profile along the melt channel of the injection nozzle to manufacture an injection molded object. Depending on a melt material being used in the process, this tolerance can become relatively narrow. For example, if there is 50–60 degrees of temperature variation in different areas of a nozzle along the melt channel, there can be areas where the melt material will prematurely solidify. This can cause mild to severe blockage of a nozzle channel, which can completely stop melt material flow in the nozzle channel.
This problem is exacerbated in the flat micro nozzles that are being designed with increasingly smaller diameter nozzle channels and that have quasi square cross sectional profiles.
Reference is made in this regard to DE 19723374 to Heitec that shows a flat nozzle having a heater located in the nozzle body along the melt channel. The heater wiring disclosed therein has an uneven distribution along the melt channel in order to compensate for the inherent heat loss that occurs at the head portion and at the tip portion of the nozzle.
Another manufacturer, Günther Heisskanaltechnik (see US Patent 2002/0102322A1), uses a flat copper jacket that uses a cartridge heater, which is mounted around the nozzle body and along the melt channel. This heating configuration attempts to address the problem of uneven heating. Unfortunately, in order to fit the copper jacket, a size of the nozzle must be increased. Hence, this method most likely will not work with micro nozzles that are arrayed to fit a certain space constraint.
Therefore, what is desired is a nozzle (e.g., a flat nozzle, a micro nozzle, or a flat micro nozzle, all referred to herein as “micro nozzle”) that balances a heating profile of the flat micro nozzle to produce consistency in melt material viscosity and speed throughout a micro nozzle channel without adding significantly to the size of the nozzle.